Omnistat wiring challenge

[dsiroky]

I've got an Omnistat RC1000 and am trying to use it to control my Hot Water boiler that runs my heating. The boiler didn't come with a 24v control line - It only had two high voltage thermostat terminals for a 120v/240v thermostat. 
 
I hooked up a 24v relay and I also hooked up a dedicated 24v transformer that does nothing other than supply 24v AC to the relay & thermostat. There is plenty of power - since the transformer is dedicated to just that.
 
I hooked up a simple 2 wire Honeywell thermostat (old school with mercury and no electronics) and tested the circuit. It all works fine with the simple 2 wire Honeywell thermostat.
 
Unfortunately, when I plug in the Omnistat and connect my 2 wires to W1 and RH - the light comes on, then turns off and it endlessly cycles this way. It sounds like the common problem I've ready about - lack of having a 24VAC common wire.
 
When I run outside to the boiler and look at the relay/transformer box I hooked up - I can hear the relay clicking and cycling away in sync with the omnistat flashing on and off. At a guess - it seems that the power stealing circuitry is triggering the relay, and I don't have other circuits it can steal power from.
 
I also don't have a spare wire to hook up a common - just the two wires for W1 and RH from boiler to furnace.
 
I looked at the specs on the optional HAI power supply module - but it appears to have too many wires for my application - and won't fit in the boiler.  Looking at the product description, it sounds like what I might need is a current limiting resistor that goes in series with the 24v relay terminals.
 
If the fix is that easy - what value resistor should be used? or am I going about this the wrong way...

 

[CJW-PIC]

Move the transformer indoors, power the 1000 R&C
Use the existing relay wires, C & W1
Good to go.

 

[dsiroky]

I think to move the transformer in doors, I would require extra wires - I only have the RH and W1 wire on the thermostat. 
 
 
The problem is that when the Omnistat tries to leach power, it lets enough current flow through the relay coil that it triggers the Omron G2R-1-SN relay and it  starts flapping the backlight..
 
http://www.ia.omron.com/data_pdf/data_sheet/g2r-_-s_ds_csm42.pdf
 
I a quick bypass of the relay today so that I could power up the Omnistat. I've disabled the backlight, and now it consistently powers up without flapping the display backlight on/off/on/off.
 
I've also confirmed that when I manually connect the wires W1 and RH it correctly triggers the relay and turns the heater on.
 
However - now when I install the thermostat and try to call for heat - I hear the relays clicking in the Omnistat - about once a minute - like it's trying to turn it on, and not succeeding. It seems to do this endlessly.

 

[ano]

As CJW-PIC says, the transformer needs to be near the thermostat.  The other side of the transformer wire needs to be connected to the common. You only need a wire from the transformer to thermostat, and they should be next to each other. 
 
A second option would be to get a bigger relay. If you get a relay that draws considerable power, the thermostat will have enough power.
 
So either move the transformer next to the thermostat and wire the common, or get a beefier 24V relay.
 
There is also a HAI/Leviton Power Supply Module, 30A00-2. I think its just a 24V transformer like you already have.